1. Field of the Invention
This invention relates to a tool wear detecting system which detects wear of a cutter in a numerically controlled machine tool during cutting.
2. Description of the Prior Art
A cutter of a machine tool is used for cutting a workpiece and gradually wears away and must be reground or replaced with a new cutter. In a numerically controlled machine tool, a tool shift command is provided from a numerical control unit, so that even if the cutter has worn away, the depth of cut and the feed rate of the cutter are not altered. Accordingly, when the cutter has worn away, the load on the tool or the workpiece markedly increases and if cutting continues, the tool may in some cases be broken. Once the tool has thus been broken it cannot be reground for further use.
There has been proposed a numerically controlled machine tool combined with an adaptive control. The adaptive control is adapted to control the feed rate, etc. of the tool so that the load on the tool or workpiece does not exceed an allowable value. Such a machine tool is free from the abovementioned defect leading to the tool breakage but has the defect of complex and expensive structure.